JPH01280769A - Photosensitive body - Google Patents

Abstract

PURPOSE:To lessen the dependency of residual potential on humidity and to improve the environmental stability of a photosensitive body by using ceramics powder and a binder resin on an under coating layer on a conductive base. CONSTITUTION:The under coating layer 3 formed by dispersing ceramics powder 4 into the binder resin 5 and a photoconductive layer 2 are successively laminated on the conductive base 1. The under coating layer 3 is formed by dispersing the ceramics powder subjected to a heat treatment in the production stage to stabilize the crystal structure into said layer and, therefore, the conversion of the ceramics powder 4 to the form of hydrate or water compd. and the consequent absorption of moisture do not arise even under high humidity atmosphere. The dependency of the residual potential on humidity is thereby decreased and the environmental stability of the photosensitive body is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a photoreceptor, and particularly to a photoreceptor having at least an undercoat layer and a photoconductive layer laminated on a conductive support.

Prior Art Conventionally, photoreceptors have been constructed by forming a photoconductive layer on a conductive support, and photoconductive materials forming the photoconductive layer include selenium, cadmium sulfide, zinc oxide, amorphous silicon, etc. inorganic photoconductive materials,
Organic photoconductive materials such as polyvinylcarbazole, phthalocyanine, trinitrofluorein, and bisazo pigments were commonly used.

However, regardless of whether the above-mentioned inorganic or organic photoconductive materials are used for the photoconductive layer, there is a problem in that its properties deteriorate depending on the manufacturing and usage conditions. Ta.

For example, if the blocking of charges at the interface between the conductive support and the photoconductive layer is insufficient, charge injection from the conductive support may occur, resulting in unfavorable properties as a photoreceptor, especially the initial charging. Problems arise such as a lower potential and an increased dark decay rate.

In addition, if there are defects, dirt, or uneven processing on the surface of the conductive support, the surface condition will be sensitively reflected in the image quality, resulting in the problem that image noise is likely to occur.
Alternatively, if the adhesive strength between the conductive support and the photoconductive layer is insufficient, the photoconductive layer may partially peel off during long-term use, causing white spots in the image area. .

Conventionally, therefore, a technique has been known in which an undercoat layer is provided between the conductive support and the photoconductive layer in order to solve the above-mentioned problems.

In addition to satisfying the above-mentioned characteristics, other characteristics required for the undercoat layer include low residual potential and no change in electrical resistance against changes in the external environment (particularly changes in humidity).

However, the reality is that no undercoat layer that satisfies all of the above characteristics has been put to practical use.

Problems that the invention aims to solve The present invention was made in view of the above-mentioned circumstances.

The present invention provides a photoreceptor having a subbing layer that has a low residual potential, excellent environmental stability, and excellent prevention of carrier injection, flat surface smoothness, adhesiveness, and the like.

Means for Solving the Problems Specifically, the present invention provides a photoreceptor comprising at least an undercoat layer and a photoconductive layer laminated on a conductive support, in which the Ogawa layer contains at least Cerami Nox powder and a binder resin. The present invention relates to a photoreceptor characterized by the following.

FIG. 1 shows an example of the structure of the photoreceptor of the present invention, in which an undercoat layer (3) is formed by dispersing ceramic powder (4) in a binder resin (5) on a conductive support (1). ) and the photoconductive layer (2) are used as self-contained layers.

The photoconductive layer (2) is provided on the conductive support (1), and may have a single layer structure in which a conventionally known photoconductive material is vapor-deposited or dispersed in a binder, or it may have a single layer structure in which a conventionally known photoconductive material is vapor-deposited or dispersed in a binder. A functionally separated structure formed by laminating a layer and a charge transport layer may be used, or a structure other than these may be used.

The conductive support (1) may be any material as long as its outermost surface is conductive, and the shape may be cylindrical or #4'13.
It can take any form such as a flexible belt or a flat plate.

The undercoat layer (3) in the photoreceptor of the present invention is a binder resin (5
), in which ceramic powder (4) is dispersed. Ceramics here refers to inorganic solid materials that have taken the form of sintered bodies or single crystals through heat treatment, and can be used. Examples of inorganic materials include alumina,
Spinel, zirconia, ittria, titania, magnesium oxide, zinc oxide.

Examples include silicon nitride, tungsten carbide, boron nitride, and the like.

The temperature of the heat treatment carried out in the manufacturing process of the ceramics differs depending on each substance, but it is sufficient as long as the materials take the form of a sintered body or a single crystal and hydrates and hydrates can be removed.

Examples of the method for manufacturing the ceramics include an alkoxide hydrolysis method (liquid phase method) in which a raw material in the form of an alkoxide is hydrolyzed and the resulting hydrolyzed product is fired at a high temperature to produce fine ceramic powder. However, it is not limited to this method; liquid phase methods such as freeze drying, solvent drying, and precipitation methods; in-phase methods such as pulverization classification method and thermal pulverization method; vapor coagulation method, gas phase reaction method, plasma method, etc. It can be manufactured by a vapor phase method or the like.

As can be seen from the above, non-ceramics, that is, inorganic materials that have not undergone heat treatment, or inorganic materials that have not taken the form of sintered mass or single crystal even after heat treatment, are hydrates or hydrates. Because it is easier to take the shape of, it is inferior to ceramics in terms of moisture resistance, heat resistance, and hardness. Therefore, dispersing non-ceramic powder in the undercoat layer as in the past is thought to be a factor in reducing the environmental stability of the photoreceptor.

The amount of ceramic powder used in the present invention is 20
~90% by weight, preferably 40-80% by weight. If the amount added is less than 20% by weight, the resistivity of the undercoat layer will be 10.
13Ω·cnl or more, the residual potential increases significantly. If the amount added is more than 90% by weight, the surface smoothness of the undercoat layer will be impaired and the dispersion stability in the binder resin will also be reduced.

The specific surface area of the ceramic powder used in the present invention is 0
, 1 to 70 i/g, particularly preferably 1 to 5 o i/g.

If the specific surface area is smaller than 0.1 Trt/g, the grain size will increase and it will be difficult to obtain sufficient resistivity. 7Qrr
If it is larger than 1/g, the particle size will become smaller and the oil absorption will be greater and the dispersibility will be worse. Moreover, it becomes difficult to handle as a powder, resulting in poor workability.

The specific resistance of the ceramic powder used in the present invention is 10
6-1013Ω・rust, especially 106-1011Ω・mouth is good. If the specific resistance is lower than 100.degree., it will not be possible to sufficiently prevent charge injection from the support when forming an undercoat layer. Furthermore, if the specific resistance is higher than 1013 Ω·m, an increase in residual potential is unavoidable.

The particle size of the ceramic powder used in the present invention is 001
~03 μm, particularly preferably 0.05 to 02 μm. If the particle size is smaller than 0.01 μm, the oil absorption will increase and the dispersibility in the binder resin will be poor. If it is larger than 0.03 μm, the surface smoothness of the undercoat layer will be impaired.

As the binder in the undercoat layer of the present invention, known thermoplastic resins or thermosetting resins can be used.

Examples of suitable binder resins include, but are not limited to, saturated polyester resins, polyamide resins, acrylic resins, ethylene-vinyl acetate copolymers, ionically crosslinked olefin copolymers (ionomers), styrene- Butadiene block copolymer, polyarylate, polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester.

Thermoplastic binders such as polyimide and styrene resin; epoxy resin, urethane resin, and silicone resin.

Phenolic resin, melamine resin, xylene resin.

These include thermosetting binders such as alkyd resins and thermosetting acrylic resins. These can be used alone or in combination.

In the photoreceptor of the present invention, a coating solution obtained by dispersing the above-mentioned ceramic powder in a binder resin can be applied by dip coating method, spray coach ink method, spinner coating method, flake coating method, or roller coating method. It can be obtained by coating the photoconductive layer on the photoconductive layer using various coating methods such as , Meyer bar coating method, etc., and drying it.

The undercoat layer of the photoreceptor of the present invention is formed to have a thickness of 0.1 to 3 μm, preferably 0.3 to 1 μm. If it is thinner than 0.1 μm, defects on the surface of the support cannot be sufficiently covered. If it is thicker than 3 μm, the residual potential tends to increase.

As the photoconductive layer used in the present invention, Sc, 5eAs
Inorganic photoconductive materials such as alloy, 5e-Te alloy, CdS, ZnO, a-8i, polyvinyl carbazole (PVK
), phthalocyanine, trinitrofluorein (1”N
F) It may be a layered structure in which an organic photoconductive material such as a disazo pigment or hydrazone is vapor-deposited or dispersed in a binder resin, or it may be a functionally separated structure in which a charge transport layer and a charge generation layer are laminated. It may be a mold configuration or a configuration other than these.

As mentioned above, the undercoat layer in the photoreceptor of the present invention is
Because the ceramic powder is heat-treated during the manufacturing process and has a stabilized crystal structure, the ceramic powder does not absorb moisture in the form of hydrates even in high-humidity environments. The humidity dependence of the residual potential can be reduced, and the environmental stability of the photoreceptor can be improved.

However, the undercoat layer of the present invention prevents the injection of charge from the conductive support to the photoconductive layer, improves the adhesion between the conductive support and the photoconductive layer, and the conductive support. Filling of surface defects in the body can be accomplished without causing inconveniences such as an increase in residual weight.

Hereinafter, specific examples of the present invention will be described.

Example 1 Epoxy resin (GY260, Ciba Geigy Japan) 10
0 parts by weight α-alumina (UA-5305, Showa Denko ■) 120 parts by weight Trichloroethane 20 parts by weight or more
After grinding and dispersing the material in a sand mill for 3 hours, an amine hardener (I-IY943, Ciba Geigy Japan) was added, and further diluted with trichloroethane to form a cylindrical aluminum support with a maximum surface roughness of 15 μm and a size of 80 x 330 mm. It was coated on the body to a thickness of 0.05 μm by the dippi-IO blowfish method. Thereafter, it was dried in a dryer at 130° C. for 1 hour to form an undercoat layer. The volume resistivity of the obtained undercoat layer was measured and found to be 1011 Ω. The maximum roughness of the surface was 0.3 μm, and it was possible to smooth out the unevenness on the surface of the aluminum support.

The above α-alumina is made into a ceramic by firing aluminum hydroxide at 1100°C, and has an average particle size Q.
, l pm, 'BET specific surface M30ya'/g,
The specific resistance was J012Ω·α.

``-undercoat layer''-- using a known vacuum evaporation device.
Under a pressure of O-5 torr, a photoconductive layer made of amorphous arsenic selenide is formed to a thickness of 50 to 55 μm! It was formed to a thickness of η.

Comparative Example 1 A photoreceptor was produced in the same manner as in Example 1, except that no undercoat layer was formed.

The photoreceptors of Example 1 and Comparative Example 1 were mounted on an EP-550 (manufactured by Minolta Camera ■) and subjected to a normal electrophotography process, and the charge potential, residual potential, image quality, and surface condition of the photoreceptor were evaluated. Measurements were taken at the initial stage and after printing 100,000 copies.

The results are shown in Table 1.

In addition, in the table, in the image quality column, ○ marks are good, △ marks are slightly degraded,
An x mark indicates a decrease, an ○ mark in the photoreceptor surface condition column indicates that no peeling of the photoconductive layer occurred, and an X mark indicates that peeling occurred.

Table 1 As is clear from the results shown in Table 1, the photoreceptor according to the example of the present invention, like the photoreceptor of the comparative example, did not significantly increase the residual potential after copying 100,000 sheets, or had poor image quality. There was no decrease in image quality, and no image noise was caused by peeling of the photoconductive layer.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the structure of the photoreceptor of the present invention. 1... Conductive support 2... Photoconductive layer 3 - Undercoat layer 4... Ceramic powder 5... Binder resin applicant Minolta Camera Co., Ltd.

Claims (1)

[Claims] 1. A photoreceptor comprising at least an undercoat layer and a photoconductive layer laminated on a conductive support, wherein the undercoat layer comprises at least ceramic powder and a binder resin.